-Although drought affects directly tree physiology and growth, the impact of secondary factors (insect pests, pathogens and fire) is often greater than the impact of the original stress and can lead to important tree mortality. In 2003, Western and Central Europe experienced a drought and heat waves that led to extensive forest damage. This paper reports on the impacts of drought and high temperatures on forest insect populations in the context of this exceptional event. Observations of changes in population levels of the main European forest insect pests during and after the drought are presented and discussed in the light of current knowledge and theories of interactions between drought and insects. We investigated the direct effects of drought on life history traits and indirect effects through physiological changes experienced by host trees. Forest pest insects were separated in 4 feeding guilds: woodborers, leaf-chewers, leaf-miners and leaf-suckers. The impact of water stress varied according to feeding guilds. Woodborers were positively influenced by prolonged water stress and the decline of host resistance. In contrast, defoliators profited better from the increased nitrogen in plant tissues linked to moderate or intermittent water stress. Field observations showed the importance of the soil water status in tree resistance against pest attacks. Thus, the 2003 drought confirmed observations from earlier droughts that, is case of bad choice of tree species in some plantations, site matching becomes a prominent and primary cause of the development of pest outbreaks. This exceptional drought may give us some indication of the impacts of extreme climatic events. However, observations of the performance at the individual level were not sufficient for predicting long-term insect population dynamics, which depends on complex interactions between biotic and abiotic factors.climate change / drought / heat wave / forest pest insect / population dynamic Résumé -Effet de la sécheresse et de la canicule de 2003 sur les populations d'insectes ravageurs forestiers en Europe centrale et occidentale. Bien que la sécheresse affecte directement la physiologie et la croissance des arbres, l'impact de facteurs secondaires (insectes ravageurs, pathogènes et feu) est souvent plus important que le stress original et peut conduire à la mortalité des arbres. En 2003, une sécheresse et des vagues de chaleur ont provoqué des dégâts importants dans les forêts d'Europe centrale et occidentale. Cet article rend compte de l'impact de la sécheresse et de la canicule sur les populations d'insectes forestiers dans le contexte de cet évènement exceptionnel. Les observations des fluctuations de populations des principaux insectes ravageurs des forêts européennes sont présentées et discutées en regard des connaissances actuelles et des théories des interactions entre sécheresse et insectes. Nous avons recherché les effets directs et indirects de la sécheresse, respectivement sur les traits d'histoire de vie et au travers des modifica...

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The precision significantly decreases for this application in the following cases: (1) physical contacts between the stylus/transmitter/receiver cables, (2) presence of magnetic objects in the surrounding of the EMT system, (3) skin and hair softness and (4) subject's head movements.

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We present a fast and robust tool for automatically converting complete polygonal scenes into volumet ric representations. A wide range of scenes are handled by storing the st atus (inside/ outside) of th e volumetric space areas in the cells of an octree. The algori thm first looks for a point in the scene for which t he status can be univocally determined. When such a point is found , it propagates its stat us to the surrounding visible cells. This iterative two-step procedure is repeated for different parts of the scene until the status of all the cells has been determined. The algorithm's advantage is t he coherence with the rendered geometry; it can handle compl ex geometry and exhibits robus t solutions for a broad range of scenes contai ning numerous artifacts, such as cracks , holes, overlapping geometries, interpenetrating meshes, double walls, and fuzzy borders.

Distal locking is one of the most difficult steps in intramedullary nailing. Numerous methods can help the surgeon, but all are time-consuming and involve much irradiation. We have developed and tested a new method based on only two fluoroscopic shots that do not need to be taken in the axes of the holes. This avoids requiring the presence of an experienced fluoroscopy operator to accurately adjust the imaging device in front of the locking holes, and decreases the exposure to radiation of the patient and medical team. A 3-D model of the distal nail and of its locking holes was constructed from a pair of calibrated fluoroscopic views. Prior to this, the contours of the nail and locking holes projections had to be determined. A 3-D optical localizer allowed the tracking of reference frames fixed to the nail, imaging device, and drilling motor. A navigation system based on the model guided the surgeon during distal targeting. The robustness, accuracy, and duration of the technique were evaluated in laboratory. The range of acceptable orientations of the X-ray beam has also been determined. Twenty drilling tests were carried out on sawbones. The accuracy and the duration required by our system to perform the distal targeting shows potential suitability for clinical use. The drill passed through the nail locking holes for all of them. The accuracy was about 1.5 mm in translation and 1 degree in rotation. The total time spent on drilling did not exceed 15 min. The system was also assessed in vivo on three patients.

-This study presents the results of a four-year trapping experiment in stands heavily infested by Ips typographus following the 1999 storms in north-eastern France. Ten bottle-traps were stapled on dead spruces or on broad-leaves in five spruce stands, among which two comprised pines, a species particularly favourable for the pupation of the predator, Thanasimus formicarius. The phenology of T. formicarius closely reflected that of its prey in all stands. We show that the proportion of pines within a 500 m radius is the main variable influencing predator/prey ratios, and that this variable alone outperforms other forest composition indices such as the Shannon diversity index estimated using all tree categories, or reduced to integrate only three categories (spruce, pine, others). These results are discussed with regard to the possible role of host trees and host-tree diversity in both insects' life-cycles and how the T. formicarius/Ips typographus ratios could be used to describe the status of Ips typographus infestations. biodiversity index / biological control / Ips typographus / Scolytidae / Shannon index / Thanasimus formicarius / Cleridae Résumé -Les ratios prédateur/proies : une mesure des populations de scolytes influencée par la composition du peuplement dans différents sites français après les tempêtes de 1999. Cette étude présente les résultats de quatre années de piégeage dans des peuplements fortement infestés par Ips typographus suite aux tempêtes de 1999 dans le nord-est de la France. Dix pièges-bouteilles ont été agrafés sur des épicéas morts ou des feuillus dans cinq pessières, dont deux comprenaient des pins, arbres particulièrement favorables à la nymphose du prédateur. La phénologie de T. formicarius a étroitement reflété celle de sa proie dans tous les sites. Nous montrons que la proportion de pins dans un rayon de 500 m est la principale variable influençant les ratios prédateur/proies, et que cette variable seule surpasse les autres indices du paysage, tels que l'indice de diversité de Shannon estimé avec toutes les catégories d'arbres, ou réduit seulement à trois catégories (pins, épicéas, autres). Ces résultats sont discutés en fonction du rôle éventuel des arbres hôtes et de leur diversité en ce qui concerne les cycles vitaux des deux insectes, ainsi que le moyen d'utiliser les ratios T. formicarius/Ips typographus pour décrire les infestations d'Ips typographus. index de biodiversité / contrôle biologique / Ips typographus / Scolytidae / index de Shannon / Thanasimus formicarius / Cleridae

We present here a method giving a robust segmentation for in vitro cells observed under standard phase-contrast microscopy. We tackle the problem using the watershed transform. Watershed transform is known for its ability to generate closed contours and its extreme sensitivity to image borders. One main drawback of this method is oversegmentation. In order to circumvent this, marked watershed based on the "modified gradient" method has been developed. However, the choice of the watershed mark locations is critical and their inadequacy may cause wrong results. Similarly to randomization and combination procedures used in the machine learning field, the present paper promotes the use of an assembly of marked watershed transforms, in order to increase the segmentation robustness. This results in the definition of candidate segmentations margins (expressed in terms of object border confidence) from which final segmentation can be chosen by means of thresholding.